There is a large need in the infrared detector industry for in process monitoring of photodiodes prior to integration into a focal plane array (FPA). An in-situ diode performance measurement will increase the yield of focal plane arrays and result in dramatic cost savings. Photovoltaic mercury cadium telluride is the material of choice for focal plane arrays due to its high spectral sensitivity and production status. However, low yield and resulting high costs of large focal plane arrays currently limit its applications. In order to ensure that future detector needs are met, the yield must be increased. One of the key issues which must be addressed in order to increase yield is that more emphasis must be placed on FPA testing. Development of techniques for microscopic mapping of materials parameters will improve material and device evaluation. A non-destructive in process control method is required which determines the electrical and optical parameters of each diode at the wafer level.